Electrically conductive threads and method of manufacturing clothing exhibiting anti-static properties therewith

ABSTRACT

A method of manufacturing clothing exhibiting anti-static properties is provided comprising preparing said clothing by sewing, weaving or knitting with at least one electrically conductive thread comprising a non-metallic bundle of natural, semi-synthetic or synthetic filaments, fibers, split fibers or tapes having a shrinkage ratio of less than 15 percent in water at 100*C. and a metallic bundle of iron, nickel, copper, brass, aluminum or stainless steel exhibiting an apparent diameter of 5 - 100 Mu , said bundles being combined under conditions which satisfy the relationship: S2 dm &gt; OR = df &gt; OR = 5 wherein df represents the denier of the non-metallic bundle, dm represents the denier of the metallic bundle and S represents the specific gravity of the metal, and the weight ratio of the metallic bundle to the non-metallic bundle ranges from 0.1 to 200 wt percent, said bundles being twisted at a tension of less than 80 percent of the strength of the metallic bundle.

United States Patent 11 1 Igarashi et al.

[54] ELECTRICALLY CONDUCTIVE THREADS AND lVIETHOD OF MANUFACTURING CLOTHING EXHIBITING ANTI-STATIC PROPERTIES THEREWITH {75] Inventors: Yoshikazu lgarashi; Yoshio Bessho; Yoshikazu Kiroku; Yasuo Takahashi, all of Okayama, Japan [73] Assignee: Kuraray Co., Ltd., Kurashiki City,

Japan [22] Filed: Mar. 30, 1971 21 App]. No.: 129,630

[30] Foreign Application Priority Data Apr. 1 1970 Japan ..45 2s720 May 13, 1970 Japan ..45/40784 [52] U.S. Cl. ..112/262, 57/157 R [51] Int. Cl. ..D05b 1/00 [58] Field of Search ..1 12/262; 57/140 R, 140 BY,

57/140 C, 140 G, 157 R, 157 ST [56] References Cited UNITED STATES PATENTS 3,025,622 3/1962 Hilton ..1 12/262 Mar. 27, 1973 3,564,834 2 1971 Elia ..57/157TS 3,611,700 10/1971 Vivien ..57/157TS Primary ExaminerPatrick D. Lawson AttorneyWilliam Kaufman and Barry Kramer [5 7] ABSTRACT A method of manufacturing clothing exhibiting antistatic properties is provided comprising preparing said clothing by sewing, weaving or knitting with at least one electrically conductive thread comprising a nonmetallic bundle of natural, semi-synthetic or synthetic filaments, fibers, split fibers or tapes having a shrinkage ratio of less than 15 percent in water at 100C. and a metallic bundle of iron, nickel, copper, brass, aluminum or stainless steel exhibiting an apparent diameter of 5 10011,,- said bundles being combined under conditions which satisfy the relationship: S dm; df 5 wherein df represents the denier of the nonmetallic bundle, dm represents the denier of the metallic bundle and S represents the specific gravity of the metal, and the weight ratio of the metallic bundle to the non-metallic bundle ranges from 0.1 to 200 wt percent, said bundles being twisted at a tension of less than 80 percent of the strength of the metallic bundle.

10 Claims, No Drawings ELECTRICALLY CONDUCTIVE THREADS AND METHOD OF MANUFACTURING CLOTHING EXHIBITING ANTI-STATIC PROPERTIES THEREWITH The present invention relates to methods of manufacturing clothing exhibiting excellent anti-static propeities and durability by sewing, weaving or knitting with threads exhibiting electrical conductivity obtained by combining bundles of natural, semi-synthetic or synthetic filaments, fibers, split fibers or tapes with bundles of metallic filaments of such metals as iron, nickel, copper, brass, aluminum or stainless steel.

It has heretofore been known to weave or knit with threads containing synthetic fibers which have been metallized by gilding, vacuum evaporation or other coating techniques. But such metal coatings tend to wear off from such electrically conductive threads as the clothing made therefrom is being washed or used. The antistatic properties, thus, are easily lost and durability also becomes inferior. This deterioration of properties which commences upon washing or use is further accelerated in sewing where the friction generated between needles and the thread tends to destroy and peel the metal that has been gilded, vacuum evaporated or coated thereon. The metal continues to peel from the damaged area during sewing, thus completely and easily reducing or even eliminating the anti-static properties as well as the durability of such clothing. I

Accordingly, it is an object of the present invention to provide electrically conductive threads and methods of manufacturing clothing therewith which exhibit excellent anti-static properties which overcome the above deficiencies.

These as well as other objects are accomplished by the present invention which provides methods of manufacturing clothing exhibiting excellent anti-static properties by employing at least one electrically conductive thread obtained by combining a non-metallic bundleof natural, semi-synthetic or synthetic fibers exhibiting less than a percent shrinkage ratio in water at 100C. and a metallic bundle of iron, nickel, copper, brass, aluminum or stainless steel, said metallic bundle having an apparent diameter of 5 to 100p. under the conditions of Sdm df 2 5 wherein:

df: denier of non-metallic bundle dm: denier of metallic bundle S: specific gravity of metal and the weight-ratio of the metallic bundle/non-metallic bundle 0.1 200 wt percent at a tension of less than 80 percent of the strength of the metallic bundle. More specifically, it has been found that when said electrically conductive thread is used in a sewing machine only as a needle thread, the tension on the needle thread is 30 to 100 gms. at a sewing machine speed of less than 2,500 rpm, the relation between the needle size and the thread count being shown in Table I. The figures are taken from Japan Industrial Standard JIS B 9076 (1962) for needles and JIS 2510, 2511, 2512 (1968) for threads respectively.

TABLE I NeedleSize:11-12,13-14,16, 18, 19-20 Thread Count: 70 80, 50 60, 36 40, 30 36, 24 3O Further, it has been found that when said electrically conductive thread is used in a sewing machine only as the bobbin thread, the tension on the bobbin thread is preferably at 5 to 20 g while other conditions can be arbitrarily chosen.

When said electrically conductive threads are use both as the needle and bobbin threads, the sewing machine rotational speedis preferably lower than 2,500 rpm, tension on the needle thread at 30 to g, tension on the bobbin thread at 5 to 20 g, respectively based on the relationship indicated in Table I.

The natural, semi-synthetic and synthetic filaments and fibers which can be employed in the present invention are, for example, cotton, rayon, cellulose, acetate, polyamide, polyester, polyacrylonitrile, polyvinyl alcohol, polyurethane, polypropylene, polyvinyl chloride, polyvinylidene chloride: and copolymers of said high polymers with other comonomers in the forms of fibers, split fibers or tapes. Blended yarns, novelty yarns, mixed yarns, plied yarns of the above-mentioned filaments and fibers can also be used. I

When filaments, fibers, split fibers or tapes of various types of high polymers having a shrinkage ratio of more than 15 percent in water at- 100C. are blended and twisted with the metallic bundles, the metallic bundles can protrude remarkably outside the thread after passing through the processes of soaping, bleaching and dyeing. Thus, it is impossible to sew with such materials in sewing machines. Moreover, the work efficiency is adversely effected as the chips from metallic bundles scatter and can hurt the eyes of the operators. The metallic bundles are also easily broken off during use and can irritate skin, causing unpleasantness.

The term bundle" as employed herein means one component of a yarn employed in the manufacture of sewing, weaving or knitting threads.

The metallic bundles employed in the present invention can be in the shape of filaments, staples or tapes. The metallic bundles may further be gilded, vacuum evaporated with other types of metals or coated with resin and oiling agents in order to prevent corrosion of the metals and to improve sewing properties within the range which does not impair the purposes of the present invention.

The apparent diameter of the metallic bundles can range from 5 to 100p. (approximately 0.5 600 deniers) and preferably from 10 to 50p. (approximately 1 deniers). If the diameter is less than 5p, it is difficult to feed yarns at the time of twisting and threads tend to get cut when manufacturing non-twisted yarns. In practice, such fine yarns are extremely difficult to manufacture and the cost thereof tends to be high. If the diameter is above 100a, the travellers employed in twisting yarns become remarkably worn and the flexi bility of such material as sewing thread even when blended is so inferior that skipped stitches and cutting of the thread are frequently observed. Moreover, the appearance thereof as well as the ability to sew therewith deteriorates. The anti-static properties of such sewing threads, such as the anti-dangling properties, deteriorate rather than improve, and the pulse discharge caused by the dielectric effect because sharper, giving tingling effects to the skin and accelerating electric shocks to the human body at the time of dressing and undressing.

When the denier of the non-metallic bundles, df, does not satisfy the formula, 8 dm 5 df 5 that is to say when df is less than 5 denier, or more than S dm, it becomes impossible or extremely difficult to twist the same with metallic bundles having an apparent diameter of 5 10011., and the manufacturing conditions of the sewing threads become extremely limited.

The limitation on the weight ratio of the metallic bundles to the non-metallic bundles is due to the remarkable consequence of the properties of the thread regarding electrical conductivity. If the weight ratio is less than 0.1 percent, sufficient anti-static properties are not imparted thereto and the threads tend to be cut often. If the weight ratio is over 200 percent, the flexibility of the electrically conductive thread deteriorates. This deterioration in flexibility adversely effects the ability to sew with such threads and also gives rise to extremely frequent occurences of scam puckering. The desirable range is 0.5 20 weight percent. The weight ratio of the metallic bundles to the non-metallic bundles is employed because of the different specific gravities of the metals used. When yarn is twisted at a tension of more than 80 percent of the strength of the metallic bundles, the metallic bundles deform considerably or are cut because of the tension and the shearing power at the time of yarn twisting. Thus, the tension should be less than 80 percent. Even in the case of non-twisted yarns, the same kind of difficulties occur either in manufacture or during use even thought there may be differences in degree.

The metallic and non-metallic bundles can be blended in such a way as to have the metallic bundle appear outside of the non-metallic bundle, or to have the metallic bundle inside the non-metallic bundle and not apparent from the outside.

The electrically conductive thread thus obtained in accordance with the present invention has an approximately similar physical appearance and sewing properties as those of sewing, weaving and knitting threads currently in commercial use and is perfectly suitable for use in sewing. Clothing made with these electrically conductive threads fully exhibit the anti-static properties thereof.

It has now become possible to obtain clothing exhibiting excellent anti-static properties as well as durability without causing any damage to the metallic bundles by sewing clothing with the conductive thread as above defined and under the sewing conditions as above defined.

The method of sewing clothing using conductive threads will now be described in detail with respect to the following three instances, namely:

1. When the conductive thread is used only for needle thread; i

2. When the conductive thread is used only for bobbin thread;

3. When the conductive thread is used for both needle thread and bobbin thread.

In the instance where the conductive thread is used only for needle thread, it has been found that the speed of sewing machines, the size of the needles and the tension on the needle thread are the primary conditions which contribute to the destruction of the metallic bundles blended into the conductive threads. It has been found that the rotational speed of the sewing machine TABLE II Size ofneedle25, 7-8 9-10, 11-12, 13-14, 16, 18

Count of threadzl00-l30, 100-130, 70-80, 50-60, 36-40, 30-36, 24-30 When a needle of the next larger size is employed as against the count of thread, the destruction decreases tremendously. The situation varies slightly if needles larger by one or more sizes are used. Accordingly, when employing the electrically conductive threads as defined in accordance with the present invention, the size of the needle and the count of the thread to be used should be in such a relation as per Table l. The needle threads have more points to come into contact with in passing through the clothing, and pulling up the bobbin thread half-way through the clothing in a lock-stitch machine. Consequently, the needle thread receives a bigger force than the bobbin thread. In normal adjustment of the tension on threads, suitable tension on the needle thread as against tension on the bobbin thread is to be provided. The adjustment of thread tension and its determination is made prior to the start of the operation. This tension is called the static tension under which the tension on the needle thread and bobbin thread is respectively indicated. In the case when conductive thread is used only for the needle thread, the tension on the needle thread must be within the range of 30 to 100 grns. Tension exceeding 100 grns will rapidly increase the destruction of the metallic bundles and that below 30 gms. will disturb meshing as the balanced tension of the needle and bobbin threads is broken.

In the case when conductive thread is used only for bobbin thread, the tension on the bobbin thread is the only factor which has any bearing and which needs to be kept within the range of 5 to gms. It is irrelevant what other conditions are employed. 7

In the case when conductive threads are used both for needle and bobbin threads, the four conditions of the rotational speed of the sewing machine, the size of needles, the tension on the needle threads and the tension on the bobbin threads, play an important role and the rotational speed of the sewing machine must be lower than 2,500 rotations per minute. Speeds exceeding 2,500 rpm will cause destruction of metallic bundles, resulting in broken pieces of metal flying about and extreme deterioration of the anti-static properties. It will be necessary to depend on Table I and to use a needle which is one size larger than that which would normally be employed. If a needle which is smaller than the right size for the thread is used, the metallic bundles are quite likely to be destroyed.

The tension on the needle thread should be kept within the range of 30 g to 100 g. When it exceeds 100 g, the destruction of metallic bundles rapidly increases and lowers the anti-static properties. When it is lower than 30 g, the mesh is disturbed as the balance between the needle thread and the bobbin thread is disturbed. The tension on the bobbin thread should be kept within the range of 5 g to 20 g. When a tension exceeding 20 g is applied, destruction of the metallic bundles can occur to a certain degree and when it is less than 5 g, the mesh becomes uneven and the commercial value of the product is damaged.

Clothing made under the above conditions employing the conductive threads of the present invention exhibit excellent anti-static properties and durability as compared with conventional clothing generally marketed.

The following examples further describe and illustrate the present invention. The methods for evaluation and measurements employed in the examples are described hereinbelow. Unless otherwise specified, all percentages and parts are by weight.

I. Anti-static property:

A polyestencotton blended material is made into a jacket, using conductive threads in a suitable manner and the jacket thus made is worn over cotton underwear, polyester underwear, polyacrylonitrile underwear, respectively, and the discharge sound and the discharge pulses seen on a synchroscope are observed and measured. The results are summarized using the following symbols:

* Remarkable discharges, extremely unpleasant XX Discharges to a considerable degree X Discharge sound heard ONo discharge sound, but discharge pulses detected @No discharge ll. Durability:

A polyester-cotton jacket made under certain conditions using the electrically conductive sewing thread was washed times in a washing machine, worn in the same manner as in the case of (l) and the anti-static property was measured in the same manner and the durability was compared with the results of (I).

III. Destruction of metallic bundles (indicated as destructiveness in the examples):

Polyester-cotton blended material was used in a suitable manner using electrically conductive sewing thread, and then the sewing thread was taken out. The thread thus taken out was untwisted and measured for the number of instances per meter where destruction of the metallic bundle had occurred and the number of such instances was indicated.

IV. Commercial value:

Polyester cotton blended material was used in making up a jacket with the electrically conductive sewing thread in a suitable manner, and points such as puckering, disturbances in meshes, and balance of needle thread and bobbin thread were observed and measured.

O Commercially acceptable X Commercially non-acceptable V. Tension on needle thread:

The points where the needle thread passes through are pre-determined in sewing machines. The thread is passed through such predetermined points and also through the needle. A tension meter or a spring balance is used to measure the tension while the operation of the sewing machine is suspended.

Vl. Tension on bobbin thread:

Bobbin thread is passed through the pre-determined points of various sewing machines (such as a bobbin in ordinary machine and a looper in a chain stitch machine) and a tension meter or a spring balance is used to measure the tension.

EXAMPLE l An electrically conductive thread comprising a stainless steel filament of 25p. twisted with three polyester filaments deniers) having the properties set forth below was used as needle thread while ordinary sewing thread comprising three twisted polyester filaments was used as a bobbin thread to sew a polyester-cotton blend jacket (polyester 65 cotton 35) under the following conditions set forth below:

The properties of the polyester filaments:

S dm 2 df 5was setat.2,l 75 5 The polyester filament used had a shrinkage ratio of 5.1 percent in C. hot water, stainless steel filament/polyester filament ratio was 15.6 wt. percent and the thread was twisted at a tension of 8.5 g which is 20 percent of the strength of the stainless steel filament. Conditions for sewing:

Rotational speed of sewing machine: 2,500 r.p.m.; 3,000 rpm.

Needle size: ll, 14

Tension on needle thread: 25 g, 30 g, 50 g, 100g,

Count of thread: 50

The anti-static properties, durability, destructiveness of the metallic bundle and the commercial values were observed.

(I) Anti-static property, durability Rotational speed of No. of times washedzlO,

'lension N0. of times washedzO on needle thread loly- Aeryl0- Poly- Acrylo- (gins) Cotton ester nitrile Cotton ester nitrile Size of sewing machine (r.p.n1.) needle 'lvnsion N0. of times wnsliedzll No. of times washed: 10 on needle Rotational speed of Size of threml lol w A cr ylu- Poly- \rrylnscwinginucliinc(111L111) needle tgms.) (otlon ester mtnle Cotton ester lllillit 2,500 .r 14 to 100 3,000 11 25 Q X X 0 X X 30 0 X X 0 X X 50 X X X X O k K O X X 100 a O O 110 0 X X 0 X X 3,000 14 25 O O X G X X 30 X X X 50 O O X O X X 00 O O X O X Y 1 I 110 8 X X 8 X X (.11) msmlctivmess, Immemial will sewing machine was lower than 2,500 rpm, the size of Tensioln the needle [4 and the tension on the needle thread at .l w Rotational speed of Silent on iii riiat l Destruc- Common 30 T 100 the best range of a good comm e rclal y sewing machine (r.p.in.) needle (gins) tiveness cizil value, 30 ll t ti t ti properties d d b l t th no 2,500 11 25 X destruction of the metallic bundles was obtained.

30 4 O Table III below shows the relationship between the 50 5 0 size of the needles and of the thread which was ob- 100 5 O tained by varying the count of sewing threads (denier no 10 O 35 offilament).

2,500 14 a n x TABLE III C) Size ofneedle: 11-12, 13-14, 16, 1s, 19 20 0 Q Thread count: 70-80,5060, 36-40,30-36, 24-30 100 U Q 40 The relationship shown in Table III was embodied in 110 s an exam le. Sewin machines were 0 erated at rota- O P g Y P tional speeds less than 2,500 rpm and 30 to I00 g ten- 11 25 X sion on the needle thread, clothin havin excellent 0 commercial values, anti-static properties and durability 50 34 O and no destruction of the metallic bundles was ob- 100 32 O tained. 110 37 0 EXAMPLE 2 3M0 14 X An electrically conductive thread of the type em 0 lo ed in Exam le 1 was used as a bobbin thread while so 21 p y p 0 an ordinary sewing thread comprising three twists of O polyester filaments (75 deniers) was used as aneedle 1m 20 0 thread in sewing a polyester-cotton blend jacket under the conditions set forth below. The anti-static properties, durability, destructiveness of the metallic bundle and the commercial values were observed. Conditions for sewing: Rotational speed of sewing machine: 3,500 rpm; 5,000 rpm Size of needle: 1 I Tension on needle thread: g Y Tension on bobbin thread: 3 g, 10 g, 20 g, 30 g Thread count: 50

(I) Anti-static properties, durability Kind of underwear (H) Dcstruetivencss, commercial value Tension on bobbin Rotational speed of sewing thread Destruc- Commermachine (r.p.m.) (grns.) tiveness cialvaluc As is clear from the above, electrically conductive bobbin thread will facilitate sewing at any high speed and contrasting conditions. The size of the needle and the tension on the needle threads used therein will not destroy the metallic bundles as indicated in Example 1. The anti-static properties and the durability obtained were excellent and it was judged that any arbitrary conditions can be employed in sewing. However, the tension on the bobbin thread must be within a certain range. Cases when the tension on the bobbin thread was made to 3 to g and to 30 g were observed in addition to the above examples, and it was found that tension on the bobbin thread in the range of 5 to 20 g results in n o destruction of the metallic bundles as well as the obtainment of excellent anti-static properties and durability.

EXAMPLE 3 Thread count: 50

The results obtained indicated that no destruction of metallic bundles was observed in instances wherein the rotational speed of the sewing machine was set to less than 2,500 rpm, the size of the needle at 14, tension on the needle thread at 30 100 g, and the tension on the bobbin thread at 5 to 20 g. Further, the anti-static properties and the durability obtained were extremely good.

The count of the sewing thread was varied in relation to the size of the needles and the instances where no destruction of metallic bundles is seen are as per Table III above.

EXAMPLE 4 An electrically conductive thread [A] comprising a 25;). aluminum filament and three polyester filaments denier) twisted together under the following conditions:

Aluminum filament/polyester filament ratio 3.3 wt percent at a tension of 6.5 g, which is 48 percent of the strength of the aluminum filament were used separately as needle threads. An ordinary sewing thread of three ply polyester filaments (75 deniers) was used as a bobbin thread to sew a polyester cotton blend jacket employing the conditions set forth below. The anti-static properties, durability, desttructiveness and the commercial value were observed. Sewing conditions:

Rotational speed of sewing machine: 1,500 rpm, 2,500 rpm, 3,000 rpm Size ofneedles: 11, 14

Tension on needle thread: 25 g, 30 g, 50 g, g,

l 10 g Count of thread: 50

rpm were applied to the electrically conductive thread B.

No. of times washed: 10

Aci'ylo- Poly- Aerylonitrile Cotton ester nitrile No. of times washed:0

(Notez) 2,500 and 3,000 rpm were applied to the electrically conductive thread A and 1,500 rpm and 2,500

QQOOX QGQOX QOOOO OOOOX OGOOX OOOOG XXXXX XXXXX OOOOO XXXXX XXXXX X X X X X X X X X X GOODS X X X X X OOQOX @0000 N0. of times washedzfl No. of times washed: 10

y- Acrylo- Poly- Acrylor nitrile Cotton ester nitrile (ll) Anti-static properties and durability of the electrically conductive thread B Tens 1 on ne 10 no! speed of of thread machine (r.p.n1.) 10 (gms.) Cotton OOOOX OOOOX OQOOQ GOOOX OOOOX M 8 XXXX xxxx OOOO xxxx XXXX xxxXX XXX @OQQO OOX X X OOOX X OOOOO 5 9 0 2 3 5 m m l 1 (l'II) DestructivencSs and commercial valiaesnol the electrically conductive threads an Kind of thread Tension A l! Rotational speed of v on needle sewmgmacluno blll) of thread Destrnc- Conlmer- Dcstruc- Common (r.p.ni.) needle (gms) tivonoss cialvaluc tiveness cial value 1,500 ll 50 X 4 53 s 51 X 62 X 1,500 14 X 0 X 0 X 0 X 3 X 2,500 11 X t83g 0 70 X 0 78 X O 69 X 0 0 55 50 0 O 40 X 100 0 Q 51 X 110 8 Q 60 X 30 36 0 50 30 O 100 O 110 O As has been described hereinbefore, the electrically 40 conductive thread A using an aluminum filament 25p. showed almost an identical result to the case in Example l where the electrically conductive thread using a 25p. stainless steel filament was used. The relationship between the sewing thread and the size of the needle it was found that substantially the same results were obtained as in Example 1 using a stainless steel filament of 25a, if the thread was within the range of the formula S dm '2 if g 5.

The electrically conductive thread B does not satisfy the formula, is dm 2 df 2 5,1311: the limited sewing conditions employed will bring about good anti-static properties and durability. However, because of the low strength of the aluminum filament, the aluminum filaments tend to be cut at the time of manufacturing the same into sewing threads, and the clothing made with 50 such threads turned out to be extremely inferior as a commercial product.

EXAMPLE 5 An electrically conductive thread comprising a copper filament (25p) coated by a dark acrylic ester resin twisted with three formalized polyvinyl alcohol spinning fibers (count of fibers obtained from an alkali coagulation bath. and dyed by dark sulfide dyes .having such relationship S dm 5 df 5 that l828 l99 was used both as needle thread and bob bin thread in sewing benzalized polyvinyl alcohol rayon blend jacket (60:40) under the same sewing conditions of Example 3.

The result obtained was that no destruction of metallic bundles was seen in the instance where the rotational speed of the sewing machine was set to less than 2,500'rpm, the size of the needle at 14, tension of the needle thread at 30 to 100 gms, and the tension of the bobbin thread at 5 to 20 g. Further, the antistatic properties and the durability obtained were extremely good.

The count of the sewing thread was variedin relation to the size of the needles and the instances where no destruction of metallic bundles is seen are as per Table I.

What is claimed is:

1. An electrically conductive thread comprising a non-metallic bundle of filaments, fibers, split fibers or tapes having a shrinkage ratio of less than 15 percent in water at 100C. and a metallic bundle exhibiting an apparent diameter of 5 100p. said bundles being combined under conditions which satisfy the relationship: S dm 2 df 5 wherein d f represents the denier of the non-metallic bundle, dm represents the denier of the metallic bundle and S represents the specific gravity of the metal, and the weight ratio of the metallic bundle to the non-metallic bundle ranges from 0.1 to 200 wt. percent, said bundles being twisted at a tension of less than 80 percent of the strength of the metallic bundle.

2. A method of manufacturing clothing exhibiting anti-static properties comprising preparing said clothing by sewing, weaving or knitting with at least one electrically conductive thread comprising a nonmetallic bundle of filaments, fibers, split fibers or tapes having a shrinkage ratio of less than 15 percent in water at 100C. and a metallic bundle exhibiting an apparent diameter of 5 lOOp., said bundles being combined under conditions which satisfy the relationship: S dm 2 df e 5 wherein df represents the denier of the nonmetallic bundle, dm represents the denier of the metallic bundle and S represents the'specific gravity of the metal, and the weight ratio of the metallic bundle to the non-metallic bundle ranges from 0.1 to 200 wt percent, said bundles being twisted at a tension of less than 80 percent of the strength of the metallic bundle.

3. A method of manufacturing clothing as defined in claim 2 wherein the electrically conductive thread is employed only as the needle thread in a sewing machine by selecting a needle size and a thread count in accordance with the following relationship:

Needle size: 11-12, 13-14, 16, 18, 19-20 Thread Count: 70-80, 50-60, 36 40, 30-36, 24-30 and sewing at a sewing machine rotational speed less than 2,500 rpm and at a tension of 30 to 100 gms on the needle thread.

4. A method of manufacturing clothing as defined in claim 2 wherein the electrically conductive thread is employed only as the bobbin thread in a sewing machine at a tension of 5 to 20 gms on the bobbin thread.

5. A method of manufacturing clothing as defined in claim 2 wherein the electrically conductive thread is employed for both needle and bobbin threads in a sewing machine by selecting a needle size and a thread count in accordance with the following relationship:

Needle size: 11-12, 13-14, l6, 18, 19-20 Thread count: -80, 50-60, 36-40, 30-36, 24-30 and sewing at a sewing machine rotational speed less than 2,500 rpm and at a tension of 30 to gms on the needle thread and a tension of 5 to 20 gms on the bobbin thread.

6. A method of manufacturing clothing as defined in claim 2 wherein said clothing is prepared by weaving with said electrically conductive thread.

7. A method of manufacturing clothing as defined in claim 2 wherein said clothing is prepared by knitting with said electrically conductive thread.

8. Clothing exhibiting anti-static properties and containing electrically conductive threads as defined in claim 1.

9. A thread according to claim 1 wherein the nonmetallic bundle is of a material selected from the group consisting of natural, semi-synthetic and synthetic materials, and the metallic bundle is of a material selected from the group consisting of iron, nickel, copper, brass, aluminum and stainless steel.

10. A method according to claim 2 wherein the nonmetallic bundle is of a material selected from the group consisting of natural, semi-synthetic and synthetic materials, and the metallic bundle is of a material selected from the group consisting of iron, nickel, copper, brass, aluminum and stainless steel.

3 3 3 UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent; No. 3 I 722 r 440 D t d March 7 1973 Inventor) Yoshikazu Igarashi et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 8, line delete "8" and insert therefor g I I In column 10, line 60, the word "desttructiveness": is misspelled and should read destructiveness In column 11 in Table II, under Tension on needle thread (gms.) "101" should read llO Signed and sealed this 21st day of May 19%.,

(SEAL) Attest:

EDWARD l l.FLETUI-IEI ,JR. C. MARSHALL DAMN Attesting Officer I Commissioner of Patents 

2. A method of manufacturing clothing exhibiting anti-static properties comprising preparing said clothing by sewing, weaving or knitting with at least one electrically conductive thread comprising a non-metallic bundle of filaments, fibers, split fibers or tapes having a shrinkage ratio of less than 15 percent in water at 100*C. and a metallic bundle exhibiting an apparent diameter of 5 - 100 Mu , said bundles being combined under conditions which satisfy the relationship: S2 dm > or = df > or = 5 wherein df represents the denier of the non-metallic bundle, dm represents the denier of the metallic bundle and S represents the specific gravity of the metal, and the weight ratio of the metallic bundle to the non-metallic bundle ranges from 0.1 to 200 wt percent, said bundles being twisted at a tension of less than 80 percent of the strength of the metallic bundle.
 3. A method of manufacturing clothing as defined in claim 2 wherein the electrically conductive thread is employed only as the needle thread in a sewing machine by selecting a needle size and a thread count in accordance with the following relationship: Needle size: 11-12, 13-14, 16, 18, 19-20 Thread Count: 70-80, 50-60, 36 -40, 30-36, 24-30 and sewing at a sewing machine rotational speed less than 2,500 rpm and at a tension of 30 to 100 gms on the needle thread.
 4. A method of manufacturing clothing as defined in claim 2 wherein the electrically conductive thread is employed only as the bobbin thread in a sewing machine at a tension of 5 to 20 gms on the bobbin thread.
 5. A method of manufacturing clothing as defined in claim 2 wherein the electrically conductive thread is employed for both needle and bobbin threads in a sewing machine by selecting a needle size and a thread count in accordance with the following relationship: Needle size: 11-12, 13-14, 16, 18, 19-20 Thread count: 70-80, 50-60, 36-40, 30-36, 24-30 and sewing at a sewing machine rotational speed less than 2,500 rpm and at a tension of 30 to 100 gms on the needle thread and a tension of 5 to 20 gms on the bobbin thread.
 6. A method of manufacturing clothing as defined in claim 2 wherein said clothing is prepared by weaving with said electrically conductive thread.
 7. A method of manufacturing clothing as defined in claim 2 wherein said clothing is prepared by knitting with said electrically conductive thread.
 8. Clothing exhibiting anti-static properties and containing electrically conductive threads as defined in claim
 1. 9. A thread according to claim 1 wherein the non-metallic bundle is of a material selected from the group consisting of naturAl, semi-synthetic and synthetic materials, and the metallic bundle is of a material selected from the group consisting of iron, nickel, copper, brass, aluminum and stainless steel.
 10. A method according to claim 2 wherein the non-metallic bundle is of a material selected from the group consisting of natural, semi-synthetic and synthetic materials, and the metallic bundle is of a material selected from the group consisting of iron, nickel, copper, brass, aluminum and stainless steel. 